producers of information, consumers of information (or the designated community), management, and the archive itself. The management component of the OAIS environment is not an entity that carries out day-to-day maintenance of an archive but a person or group that sets policies for the content contained in the archive. The OAIS model also defines an information model. Physical or digital items which contain information are known as data objects. Members of the Designated Community for an archive should be able to interpret and understand the information contained in a data object either because of their established knowledge base or with the assistance of supplementary "representation information" that is included with the data object. An information package includes the following information objects: Content Information: this includes the data object and its representation information Preservation Description Information: contains information necessary to preserve its affiliated content information (such as information about the item's provenance, unique identifiers, a Checksum or other authentication data, etc.) Packaging Information: holds the components of the information package together Descriptive Information: metadata about the object which allows the object to be located at a later time using the archive's search or retrieval functions There are three types of information package in the OAIS reference model: Submission Information Package (SIP): which is the information sent from the producer to the archive Archival Information Package (AIP): which is the information stored by the archive Dissemination Information Package (DIP): which is the information sent to a user when requested These three information packages may or may not be identical to each other. The functional model There are six functional entities in an OAIS: Ingest function: receives information from producers and packages it for storage. It accepts a SIP, verifies it, creates an AIP from the SIP, and transfers the newly created AIP to archival storage Archival Storage function: stores, maintains, and retrieves AIPs. It accepts AIPs submitted from the Ingest function, assigns them to long term storage, migrates AIPs as needed, checks for errors, and provides requested AIPs to the Access function Data Management function: coordinates the Descriptive Information of the AIPs and the system information that supports the archive. It maintains the database that contains the archive's information by executing query requests and generating results; generates reports in support of other functions; and updates the database. Administration function: manages the daily operations of the archive. This function attains submission agreements from